Artificial fingers are used in prosthetics and also in handling technology, where robots or handling systems are equipped with finger-bearing grippers. In use on prosthetic hands, prosthetic fingers are needed to functionally or visually replace missing fingers of a natural hand. For robots or handling systems, artificial fingers should simulate the flexibility of the human hand. In the present description, both technical gripping elements and also prosthetic components are meant when speaking generally of fingers, otherwise the nature of the fingers is specifically indicated. Gripping mechanisms are understood to be both prosthetic hands and also technical grippers, end-effectors and handling mechanisms. Aside from passive prosthetic fingers, which predominantly have a cosmetic function and which are mounted on a base in a non-actuating manner, it is necessary to actuate fingers to actuate relative to a base in order provide a gripping mechanism with which objects can be gripped. In the simplest case, a rigid finger is mounted in an articulated manner on the base and coupled to a cable system which causes flexion against a resetting spring during actuation.
Many different actuating mechanisms for prosthetic fingers are known from WO 2010/018358 A2. In addition to cables, which can be operated directly via motors fixed on the base or which are fixed on a movable yoke, direct drives for displacement of the proximal members relative to the base by means of gears or spindles are disclosed. In addition, a coupling of a secondary member to a proximal member via a separate band element is shown, so that an automatic flexion of the secondary member is made during a flexion of the proximal member.
DE 600 23 142 T2 relates to a movable finger for a prosthesis with a base in which a drive is mounted. A flexion of an intermediate portion may occur via a wire, which is attached to a spindle nut; resetting when the drive is reversed is undertaken by means of an intermediate portion spring. A plurality of distal members may be bent via a cable system.
WO 2011/087382 A1 relates to a modular prosthetic hand with mechanically independent finger modules, in which an electric motor with a gear is arranged within a proximal section of the finger. Via a multi-link system, a distal element can be pivoted relative to a proximal element upon adjustment of a worm gear, while at the same time a force is transferred via a coupling rod in order to pivot the proximal element relative to the base.